Central and peripheral inputs in sweating regulation during thermal transients

Area of Science:

• Human physiology
• Thermoregulation
• Environmental health

Background:

• Understanding human sweating regulation is vital for predicting responses to thermal stress.
• Existing models often simplify the complex interplay of core and skin temperature in thermoregulation.

Purpose of the Study:

• To investigate the relationship between core and skin temperatures and local sweating response during transient thermal loads.
• To determine if a simple additive model sufficiently explains sweating regulation or if a more complex interaction is necessary.

Main Methods:

• Eight nude men were subjected to controlled heating-cooling cycles with varying temperature slopes.
• Continuous measurement of rectal, esophageal, and mean skin temperatures.
• Local sweating response was assessed using an arm chamber under a thermal clamp.

Main Results:

• A simple additive model of core and skin temperatures is insufficient to explain sweating regulation.
• A multiplicative interaction between mean skin and core temperatures is necessary to describe the central drive for local sweating.
• Observed interindividual differences suggest a nonlinearity in the thermoregulatory system's response.

Conclusions:

• Human sweating regulation during dynamic thermal conditions is complex, involving multiplicative interactions between core and skin temperatures.
• The findings necessitate a revised understanding of thermoregulatory models to incorporate these dynamic interactions.
• Individual variations in thermoregulation point to nonlinear system responses that warrant further investigation.